Exploring Halotolerant Phosphate-Solubilizing Bacteria Isolated from Mangrove Soil for Agricultural and Ecological Benefits

Abstract

Phosphorus is a vital element for all life forms. Phosphate-solubilizing bacteria transform phosphate into a bioavailable form through solubilization and mineralization processes. The aim of this study is evaluating the role of halotolerant, phosphate-solubilizing bacteria (PSB). having different PGPR traits as biofertilizers. Thirteen bacterial strains were isolated from soil samples of Ras Muhammad mangrove forest and screened for production of different PGPR traits. The most potent microbial candidates were identified by rRNA gene sequencing analysis and uploaded in GenBank as Bacillus safensis [OR341132] and Cytobacillus firmus [OR431197] these showed ability to tolerate salt concentration up to 10%, can fix nitrogen by growing on nitrogen free media with excellent growth and characterized qualitatively and quantitative solubilize phosphorous more than 100µg/ml of insoluble phosphate,  hydrolyse phytate and produced IAA showing the highest value in the range of 94.54, 220,38 μg/mL respectively. In pot trials performed in a greenhouse the isolated strains Bacillus safensis [OR341132] and Cytobacillus firmus [OR431197] were able to significantly improve levels of assimilated phosphate, compared to non-inoculated plants.  Moreover, mixed treatment (Bacillus safensis +Cytobacillus firmus ) increased soil fertility and consequently improve the growth of parley plant . The study has overall concluded that bacteria isolated from mangrove soil, Bacillus safensis [OR341132] and Cytobacillus firmus [OR431197] could be used as the halotolerant plant growth-promoting rhizobacteria [HT-PGPR] and phosphate-solubilizing bacteria [PSB] and have a good influence on the health of barley [genotype Giza123] plants under salinity conditions during thirty days.